Belt drives for sewing machines



Dec. 13, 19 F. L. WALLING ETAL 2,964,001

BELT DRIVES FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed June 30, 1958INVENTOR. Francis L. Walling and BY SIan/ey M. Sliva g 9 ATTORNEY Dec.13, 1960 w 1 ETAL 2,964,001

BELT DRIVES FOR SEWING MACHINES Filed June 30, 1958 2 Sheets-Sheet 1 "Wv 14mm? I mmm i i i a i s Francis L. Walling a d 39 4O 2 BY Stanley M.Silva XQQV AT TORNEY United States Patent Ofitice 2,964,001 PatentedDec. 13, 1960 BELT DRIVES FOR SEWING MACHINES Francis L. Walling andStanley M. Sliva, Trumbull,

Conn, assignors to The Singer Manufacturing Company, Elizabeth, N.J., acorporation of New Jersey Filed June 30, 1958, Ser. No. 745,616

2 Claims. (Cl. 112220) This invention relates to sewing machines and,more particularly, to a novel belt drive between the arm shaft and bedshaft of a sewing machine.

It is an object of this invention to provide a belt drive between spacedshafts of a sewing machine in which the shafts will partake ,of turningmovement in opposite directions of rotation.

In the conventional sewing machine construction, an arm shaft whichdrives the needle bar and the needle thread take-up and a bed shaftwhich drives the looptaker are interconnected for rotation in timedrelation. The direction .of rotation of arm and bed shafts differs inthe various sewing machines presently established in the trade. In theevent that it is desired to employ a needle bar and take-up mechanism ofone established sewing machine design, such as the link take-upmechanism as disclosed in the United States patent of Kaier, No.2,206,285, July 2, 1940, in combination with a bed shaft and loop-takermechanism of a different established and proven design, such as thatdisclosed in the United States patent of Parry, No. 2,314,513, March 23,1943, the problem arises that the proper direction of rotation of thearm and bed shafts must be maintained.

The present invention provides a novel and effective construction bywhich opposite directions of rotation may be attained between the armand bed shafts of a sewing machine where a timing belt is used todrivingly interconnect the shafts.

With the above and additional objects and advantages in view as willhereinafter appear, this invention comprises the devices, combinations,and arrangements of parts hereinafter described and illustrated in theaccompanying drawings of a preferred embodiment in which:

Fig. 1 represents a side elevational view of a sewing machine embodyingthe invention, with portions of the sewing machine frame illustrated inverticfl cross section,

Fig. 2 is an enlarged cross sectional view, taken substantially alongline 2-2 of Fig. 1, showing the details of the idler pulley,

Fig. 3 is a vertical cross sectional view of the sewing machine standardtaken substantially along line 3-3 of Fig. 1, illustrating the beltdrive between the arm and bed shafts, and

Fig. 4 is a vertical cross sectional View of the upper portion of thebracket arm taken substantially along line 44 of Fig. 1, illustratingthe arm shaft sprocket pulley and the idler pulleys.

Referring particularly to Fig. 1 of the drawings, the sewing machineframe comprises a bed 11 from which rises a hollow standard 12supporting a bracket arm 13 which overhangs the bed.

Journaled for rotation in the bed is a bed shaft 14 to which is fixed aninternal gear 15 which meshes with a pinion 16 carried on a short hookshaft 17 journaled in the bed. A conventional rotary hook 18 is fast onthe hook shaft. This hook driving mechanism beneath the bed isconventional and is similar to that disclosed in the United States ParryPatent No. 2,314,513. The op- 2 eration of the rotary hook requires thatthe bed shaft 14 be rotated in a clockwise direction as viewed in Fig. 3and as indicated by the arrow thereon.

Iournaled for rotation in the bracket arm and substantially parallelwith the bed shaft 14 is an arm shaft 20 which has fast thereto a handwheel pulley 21 by which power is transmitted to the sewing machine.Fixed on the arm shaft within the bracket arm is a counterbalance 22which carries an offset crank pin 23. A needle thread take-up lever 24fulcrumed in the bracket arm is actuated by means of a drive link 25which embraces one portion of the crank pin 23. A needle bar drive link26 embraces the offset portion of the crank pin 23 and is pivoted inturn to a needle bar 27 which is carried for endwise reciprocation inbushings 28 in the bracket arm and has secured at its lower extremity aneedle 29 which cooperates with the rotary hook 18 in the formation oflock stitches. The needle and take-up driving mechanism in the bracketarm is conventional and is similar to that disclosed in the UnitedStates Kaier Patent No. 2,206,285. The operation of the needle bar andtake-up actuating mechanism requires that the arm shaft 20 be rotated ina counterclockwise direction as viewed in Fig. 3 and as indicated by thearrow thereon.

The belt connection by which the arm and bed shafts are drivinglyinterconnected for rotation in opposite directions of rotation comprisesa continuous belt 31 to which is secured evenly spaced lugs or clips 32which extend on both the inside and the outside of the belt. The beltillustrated in the drawings is preferably formed of a plurality of turnsof fiber with metallic clips .crimped thereon. A molded belt of rubber,plastic, or a combination of these materials would also serve in thisinvention. Identical sprocket wheels 33, 34 are secured on the arm shaft20 and bed shaft 14, respectively, in substantially vertical register,that is, with the corresponding points on each sprocket pulley disposedin a common plane.

The bracket arm of the sewing machine frame above the standard is formedwith an upwardly open slot 35 which exposes the sprocket pulley 33 onthe arm shaft. A bridge piece 36 spanning the slot 35 is secured to thebracket arm on both sides of the slot to strengthen the machine frame.At one side of the slot 35, preferably on that side toward the handwheel, the bracket arm is formed with a pair of outwardly projectinglugs 37 each of which is apertured to accommodate a crank 38. As bestillustrated in Fig. 2, the cranks 38 are each formed with an offsetcrank pin 39 extending from a flange 40 and are threaded, as at 41, toaccommodate a washer 42 and a lock nut 43 serving to clamp the crank tothe lug 37 in selected angular positions of the crank pin 39. The crankpins 39 are disposed parallel to the arm shaft 26 and by means of thelock nuts 43 may be selectively adjusted toward and away from the armshaft.

Journaled freely for rotation on the crank pins 39, preferably on needlebearings 44-, are a pair of idler pulleys 45 which are maintained on thecrank pins by means of washers 46 and nuts 47 which engage threadedportions 48 on the extremities of the crank pins.

Referring to Figs. 3 and 4, the crank pins 39 and the idler pulleys 45are arranged on opposite sides of the arm shaft 20, one of the idlerpulleys being disposed above and at one side of the arm shaft while theother idler pulley is disposed below and at the opposite side of the armshaft. The driving belt 31 is arranged such that the inside of the beltengages the sprocket pulley 34 on the bed shaft and both idler pulleys45, while the outside of the belt engages the sprocket pulley 33 on thearm shaft.

With this construction, a reverse belt drive is attained readily andconveniently in a sewing machine frame.

The continuous belt is maintained in a vertical position with thecorresponding points of the belt in a fixed plane, and the tautness ofthe belt may be adjusted readily by an angular adjustment of the crankpins 39 without influencing the timing between the arm and bed shafts.

Having thus set forth the nature of this invention, what we claim hereinis:

1. In a sewing machine having a frame including a work supporting bed, abracket arm overhanging said bed, an arm shaft journaled in said bracketarm and a bed shaft journaled in said bed substantially parallel to saidarm shaft, means for drivingly interconnecting said am and bed shaftsfor turning movement in opposite directions of rotation, comprisingsubstantially co-planar sprocket pulleys secured one on said arm shaftand one on said bed shaft, said bracket arm being formed with anupwardly open slot exposing said sprocket pulley on said arm shaft, afirst idler pulley disposed in said slot, means journaling said firstidler pulley in said bracket arm on an axis parallel to, above, and atone side of said arm shaft, a second idler pulley disposed on said slot,

means journaling said second idler pulley in said bracket arm on an axisparallel to, below, and at the opposite side of said arm shaft from saidfirst idler pulley, a continuous belt, evenly spaced lugs carried onsaid belt and extending on both the inside and outside thereof, the

outside of said belt disposed in engagement with the sprocket pulley onsaid arm shaft, and the inside of said belt disposed in engagement withboth said idler pulleys and with the sprocket pulley on said bed shaft.

stantially parallel to said bed shaft, means for drivinglyinterconnecting said shafts for turning movement in opposite directionsof rotation comprising a sprocket pulley fast on a free extremity ofsaid bed shaft, a sprocket pulley fast on said a=rm shaft between saidbearings, a first idler pulley journaled on the free extremity of a studshaft in said frame and disposed above and sutficiently to one side ofthe axis of said arm shaft sprocket pulley such that a line which istangential to the pitch circles at one side of said idler pulley andsaid bed shaft sprocket pulley extends outwardly beyond the periphery ofsaid arm shaft sprocket pulley, a second idler pulley journaled on thefree extremity of a stud shaft in said frame and disposed beneath andsufficiently to the opposite side of said arm shaft sprocket pulley suchthat a line which is tangential to the pitch circles at one side of saididler pulleys extends outwardly beyond the periphery of said arm shaftsprocket pulley, a continuous belt, evenly spaced lugs on said belt anddisposed on both the inside and the outside thereof, the inside of saidbelt being disposed in operative engagement with both of said idlerpulleys and with said bed shaft sprocket pulley, and the outside of saidbelt being disposed in operative engagement with said arm shaft sprocketpulley.

References Cited in the file of this patent UNITED STATES PATENTS

